Muffle furnace



. 1,607,681 l.. w. MANloN MUFFLE FURNAGE ori. :mal Filed Deo. 14, 1921 3 Smets-511 l Nov. 23 1926.

m m L Samva? L. w. MA N|ON MUFFLE FURNACE original Filed neo. '14, 1921 Nov. 23 1926.

atboz M136 1,607,681 L. MANION MUFFLE FURNACE Original Filed Dec. 14, 1921 3 Sheets-Sheet 5 Leo W. /Wam'oz 61H01 wend Patented iNov. 23, 192:3'.

UNITED STATES PMENTg OFFICE.

LEO W. MANION, OF CANTON, OHIO.

Application lll-ed December 14, 1921, Serial No. 522,251. Renewed June 4, 1926.

This invention relates to improvements in Inutile construction for furnaces such as are vused for burning or fusing enamels on steel or cast iron Ware, or for annealing, heat treating or tempering or other purposes where it may be desirable or necessary to prevent the gases of combustion from coming into contact with the articles within the burning or working chamber.

The enamels must be burnt or fused in a chamber free from' smoke and gases of combustion which would dull thegloss upon the enamel. It is usual to provide a mulle or inner lining in the furnace, the ware`being lplaced within the chamber surrounded by the mule, while the heated gases completely surround the muflle, but are prevented from passing into the burning chamber and into contact with the ware.

In order to obtain the proper working temperature within the burning chamber, it is necessary to produce a considerably higher temperature outside of and around the muliie. a considerable loss taking lace in conducting heat through the mu e. The muftle tile must necessarily be thin tov allow for proper radiation and the exceedingly high temperatures quickly burns out these tile by developing cracks which allow gases and smoke 'to enter the burning chamber ruining the ware. V

The objects ofthe present invention are to provide a mule type furnace 1n which the Inutile is so constructed to produce a consderably larger radiating'area than is possible with the usual form of mule furnace and to provide an improved'constructionof tile in the maille which increases the rad1ation of the .mule, and decreases the pos-A 40 siblity of cracking or breaking of `the mule from expansion and contraction due to changes in temperature and also which considerably lessens the cost of installing or repairing the mutlle.

The invention thus set forth in general terms is illustrated in the accompanying drawings in which- Figure 1 is a longitudinal sectional view through a furnace embodying the mventlon; Fig. 2, a section on the line 2 2, Flg. 1; Fig. 3, a section on the line 3'-3, Fig. l2; Fig. 4, a erspective view of one of the tile used in tlie bottom wall of the mullle;

-Fig. 5, a perspective view of one of the tile used in the supporting arches of the mame;

Fig. 6, one of the tile carried by the supporting arches; and t 1Fig. 7, one of the lower row ofside wall Similar numerals refer to similar throughout the drawings.

The combustion -chamber 1 may be of parts usual construction, being provided with the bottom'vvall 2, side and end walls 3Y and 4 respectively, and the spaced piles or piers -located in parallel rows through the combustion chamber allowing the gases of combustion which enter at the inlets 6 to pass entirely through the combustion chamber and between the piles.

In the usual forgn of muftle type furnace now in general use, it is common to provide a row of space d piles or piers only along each side of the combustion chamber, an arch, which forms the bottom part of the burning or working chamber bein spanned across said rows of piles. Space walls of lire brick are then built upon the arch to receive the burning racks upon which the ware is placed.

It will be seen that this arch, in order to support the weight placed'y thereon, must necessarily be of considerable thickness, the radiation therefrom being considerably reduced as the heat from the combustion chamber must pass through the thicknsvof eliminated, the bottom wall of the mulile may be constructed of considerably lighter tile, thus rovidin-g several times the radiation whic is possible with the old form of furnace.

The bottom wall of the mullle is constructed of tiles 72 each of which is provided with the thin panel S. These tiles may have tongues and grooves 9 and 1'0 respectively at opposite ends. and 11 and 12 respectively at. opposite sides, 'by means of lll) which adjacent tiles are interlocked, or plain or lapped joints may be provided.

As best shown in Fig. 2, these tiles are supported upon their lower side edges on the piles 5, the upper side edges engaglng the next adjacent tiles, thus forming a saw tooth bottom wall in the burning chamber. The

supporting the burnin racks upon which the ware is placed in t e burning chamber.

In the common type of furnace above referred to in which the arch bottom wall is used, it is necessary to provide extremely large piers or piles within the combustion chamber to support the opposite sides of the arch, a very small space bein left between the arches for the passage o `the gases of combustion. These piers amount of heat from the gases ,of combustion and to ether with the walls upon the top of thefarc which support the burning racks, allow for very little radiation upon the under side of the ware. Especiall in the treatment of enamel ware, it has en found essential to heat the under side of the ware to a very high temperature, in order to cause the enamel to fuse with the metal.

With the present construction, the tiles forming the bottom wall' of the heating chamber or muille require very small piers to support the same, it being only necessary to provide piers of sullicient size to support the edges of the tiles. As the-tiles forming the bottom wall are supported at their lower edges upon the piers vand at their upper edges upon the next adjacent tiles, the structure produced is of great strength, while the radiating surface beneath the working chamber is also considerably increased, the heat radiating from every portion of these bottom tiles.

The side and upper walls of the muffle comprise the spaced columns and arches 14 between which the thin walls 15 are carried. These arches are formed of heavy tiles such as shown at,16 in Fig. 5 and may be composed of cheaper material such as lire clay,y

while the thin walls 15 are composed of the `tiles 17 which may be formed of siliconcarbide or suitable heat resisting alloy metals, which have many times the thermal conductivel as well as mechanical strength of the ordinary refractories.

Each of the arch tiles 16 is provided in itsupper and lower edges with the respective ton ues and grooves 18 and 19 by vet means o which these tiles are connected and each of these tiles is provided in its side edges with the grooves 20 which receive the side edges of the thin tiles 17. The tiles 17 are also provided in their upper and lower edges with the respective tongues and grolpves 21 and 22 for binding the same toet er. g The bottom row of tiles 16* in each side absorb a great' wall are all made as thick vas the tiles 16 andas long as the bottom wall tile 7 so as to span from the middle of one pile 5 to another; and the tiles 16a are provided with the proper tongues and grooves to form joints with eachother, and with the adjoining tiles,

asv shown in Fig. 7. peaks thus formed at 13 provide means for v ably less material, thus reducing the cost of the same, while the arch tiles 16 are formed of a cheaper material, thus reducing the initial costof the mullle as well as the upkeep of the same.

It will also be seen that the thin tiles 17 may be permitted to move within the groove' 20 of the arch tiles, due to expansion and contraction, owing to changes in temperature, thus considerably reducing the possibility of breaking or cracking of these tiles from the excessive temperatures to which they must necessarily be supjected.

By referring to Fig. 3 o the drawings, it will be seen that the upper portion of the muille is supported from the outer wall 3 of the furnace by the horizontal wall 2l which extends from the rear end of the furnace to a point intermediate the 'ends thereof, openings 25 being provided in said wall near the front end of the furnace.

The stack 26 is connected with the rear end of the furnace above the` mulile, thus causing the gases of combustion to be drawn upwardly from the combustion chamber through the piles 5 and/between the mulile and the outer wall of the furnace Iand then forwardly to the openings 25, the gases then being drawn 'rearwardly over the entire top wall of the muflle to the stack.

The ases will-thus entirely surround the mulile, eating the same to a high temperature, the heat being radiated through the thin walls of the maille to the burning chamber. The usual door opening 27 is provided in the forward end of the burning chamber to permit the ware to be placed therein or removed therefrom and is normally closed by asuitable door 28.

It will be evident from the above that a muille furnace is thus provided which may be installed at considerably less cost than the common form of mulllefurnace in which refractories of the same uality are used and which will be capable o? erably greater radiation than is possible producing considchamber and the combustion chamber is considerably reduced. In the usual form of mufile furnace it is necessary to raise the temperature of the combustion chamber to 26000- to 3000 F. in order to produce a temperature of 1800 F. within the burning chamber while with the present construc-v tion a temperature of 1800 F. maybe produced within the burning chamber by raising the temperature of the combustion chamber to only '2000 4to 2200 F. This is a great advantage in the operation of the furnace as the excessive heat which it is necessary to maintain in the combustion chamber of the ordinary form of furnace will quickly burn out the refractories comprising the muliie.

For these reasons the improved furnace can be operated with less fuel, than has heretofore been required; and the intervals between the V-shaped ridges in the bottom wall, permit the entrance of the fork usually employed for charging and withdrawing `ware from the furnace.

I claim 1. In a furnace of the character described, a mule provided with a bottom wall of substantially uniform thickness throughout its area having alternate similar ridges and de pressions, the ridges being arranged to support burning racks and the depressions being arranged to receive charging forks.

2. In a furnace of the character described, a mulile having a bottom wall of substan- `a muiie having a bottom wall formed of a plurality of parallel rows of oppositely in-- clined tiles, means for supporting thelower edges of said tiles, the upper edges of adja- 'cent rows of tiles being joined together to close the wall and support burning racks. 4. In a furnace of the character described,

Y a mulile having a bottom wall of substantially uniform thickness throughout its area comprising a plurality of parallel, V-shaped sections, and means below .said muiiie for supporting the lower edges of said sections.

5. In a furnace of the character described, a mule having side an'd top walls composed of spaced columns and arches of refractory material and relatively thin walls of refractory'material carried by said columns and arches.

6. In a furnace of the character describedl a muie having side and top walls formed of spaced columns and arches of relatively heavy refractory material, said columns and arches having grooves ,in opposite sides and tiles 0f relatively thin refractory material located in said grooves.

7. In a furnace of the character described,

a muie having side and top walls comprising spaced arches of relatively heavyslightly .refractory material and relatively light tiles of highly refractory material supported by said arches.

8. In a furnace of the character described,.

a muiiie, a combustion chamber below the Inutile, and a corrugated floor wall for the muie forming the roof of thev combustion chamber and comprising similar ridges and depressions arranged to support burning racks and to receive charging forks respec-- tively.

LEO W. MANION. 

